This invention relates generally to the containment of individual battery cells that make up a vehicular battery pack, and more particularly to the use of extruded components that make up at least portions of a battery enclosure to promote sealed containment of the individual battery cells.
Lithium-ion and related batteries are being used in automotive and related transportation applications as a way to supplement, in the case of hybrid electric vehicles (HEVs), or supplant, in the case of purely electric vehicles (EVs), conventional internal combustion engines (ICEs). The ability to passively store energy from stationary and portable sources, as well as from recaptured kinetic energy provided by the vehicle and its components, makes such batteries ideal to serve as part of a propulsion system for cars, trucks, buses, motorcycles and related vehicular platforms. In one form suitable for automotive applications, individual battery cells are combined into larger assemblies such that the current or voltage is increased to generate the desired power output. In the present context, larger module and pack assemblies are made up of one or more cells joined in series, parallel or both, and include additional structure to ensure proper installation into the vehicle. Although the term “battery pack” is used herein to discuss a substantially complete battery assembly for use in propulsive power applications, it will be understood by those skilled in the art that related terms—such as “battery unit” or the like—may also be used to describe such an assembly, and that either term may be used interchangeably without a loss in such understanding.
In one form, the individual cells that make up a battery pack may be configured as rectangular (i.e., prismatic) cans that define a rigid outer housing known as a cell case. In another form, the individual cells may be housed in a thinner, flexible rectangular pouch. Both variants can be placed in a facing arrangement (much like a deck of cards) along a stacking axis formed by the aligned parallel plate-like surfaces. Positive and negative terminals situated on one or more edges on the exterior of the cell housing are laterally-spaced from one another relative to the stacking axis and act as electrical contacts for connection (via busbar, for example) to an outside load or circuit. Regardless of which variant is employed, design goals associated with the enclosure used to contain the stacked individual cells include its ability to provide secure attachment to and containment within the corresponding vehicle compartment, as well as some degree of sealed gaseous, liquid, thermal and electrical isolation from the ambient environment. Traditionally, this has necessitated the use of enclosure assemblies that are complex and expensive, especially as it relates to reducing or eliminating enclosure joints that are incompatible with such goals. Examples of such complex or expensive enclosures include those constructed through welding, bonding or riveting of steel-based components, while others used simple plastics that make it difficult to maintain battery dimensional quality and durability or composites that involve expensive materials and fabricating techniques.